Spinning a big aluminium hemisphere - aka, sanding R2D2s dome

Looking for some ideas. I’m building a mostly 3D-printed 1:1 scale R2D2. I say “mostly” because aside from the electronics and motors, the only significant non-printed part is his dome which I opted to make out of aluminum. I didn’t make this part, there are folks out there who manufacture these specifically for droid builders.

But I do need to sand it, and ideally end up with a spun aluminum finish on it in the end. I could do this the old fashioned elbow grease way, but I’m looking for ideas for how to speed up the process and I think end up with a better looking end product.

One idea that comes to mind is using the Laguna lathe to spin the dome at a relatively slow speed while using wet sanding and scotchbrite pads. I imagine I could rotate the headstock like you would if you were turning a large bowl, then make some sort of chuck out of wood that clamps onto the top of the dome through the hole you see there? @CLeininger, curious for your thoughts on this idea.

Any other ideas come to mind?

Afix it to a turntable of some sort and hold some sandpaper to it while it’s spinning?

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The lathe will work provided the diameter isn’t too big. My only concern is getting aluminum sanding dust inside the motor housing and the chuck, so make sure you cover all exposed areas and do a thorough cleaning afterward.

Good call on the dust. I was thinking of moving the headstock into the outboard position if the diameter is too big for the normal position. I was reading a bit about this on the Lagunas and it looks like you just take the tailstock off, then slide the whole headstock and motor unit down the ways to the end rather than rotating the headstock like I’ve seen on other lathes. Does that sound right?

Hmm good question. I haven’t tried moving the headstock. The main thing is to make sure it is exactly centered when moved back in place. I plan on doing some turning tomorrow or Monday and will take a look

To add on to what @Devmani mentioned - the turntable idea. If you could get your hands on a high quality cake decorating turntable, it might be worth considering. The high end ones are heavy, and have a really smooth and flat spinning motion (I assume they use ball bearings). I don’t know the specific brand, but it is what they sell at the cake supply store called Make It Sweet, located at 183 and Burnet. You could just look at them there, and see if it would meet your needs.

There’s literally an entire Austin group that builds R2D2s

http://www.centraltexasdroids.com/

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Pottery wheel…

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Does the space have one?

No. Talked about, but logistics surrounding a kiln is in the way of any pottery area.

We’re also too strapped for space to do a ceramics area right. It is on the horizon for our next location down the road.

Makes sense. I loved the ceramics area of my last makerspace in Washington. Learned so much and actually made a lot of the dishes I use today. Eating lunch out of one of my bowls as we speak. :smiley:

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Watch out! We may be calling on you to be a ceramics steward someday :awesome:

Did you happen to look into this at all? I’m considering trying it in the morning.

Watched Laguna’s video on aligning centers and it seems unlikely that I’d get it out of alignment, but simple to adjust if I do.

@csader got it figured out, works like a champ.

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And for reference, everything went back together and realigned itself perfectly.

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Sorry for the late reply. I’ve been slammed at the shop and haven’t looked at Discourse in a few days. Glad you guys were able to figure it out!

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